FairFIL boosts Ethereum censorship resistance by 10x cost

A new research paper by Patrick Spiesberger and Hannes Hartenstein introduces Fair Forward Inclusion Lists (FairFIL), an accountable censorship resistance mechanism for Ethereum. The paper argues that current proposals like FOCIL (scheduled for late 2026) fail to hold committee members accountable: an adversary could bribe the entire committee to omit a transaction for under €2 per block. FairFIL closes this gap by requiring every builder to publicly disclose all transactions they choose to censor, subject to a protocol-anchored policy. A committee then verifies the completeness and validity of that disclosure. Crucially, the next builder must include those previously censored transactions or forfeit the full block reward.

This design forces rational participants to comply: extending censorship beyond a single slot becomes economically irrational because losing a block reward (currently worth thousands of dollars) dwarfs any potential bribe. Empirical evaluation on Ethereum mainnet shows multi-block censorship costs under FairFIL are one order of magnitude higher than under FOCIL. Meanwhile, builders retain most of their MEV extraction freedom—only the ability to delay time-critical transactions is checked. The authors also present initial measurements indicating that the required mempool consistency (all builders seeing the same pending transactions) already holds in practice, making FairFIL feasible for deployment.